Illumination device using LED has been disseminated as one solution for addressing recent subjects on energy saving. LED is characterized by its low power consumption and long service life, and is said to be a fast-evolving semiconductor device, with relevant technologies under investigation worldwide.
While LED in the early days have been limitedly applied to low-power-consumption appliances such as indicator lamp and so forth, there have emerged in recent years high-output illumination devices which incorporate high-output LED elements having been developed. The LED illumination devices are very high in illumination effect, and some of them surpass fluorescent lamps. By virtue of straightness of illumination, LED has high illuminance value relative to the total luminous flux, and can emit strong light. LED is also expected to operate over 60,000 hours if used under optimum conditions.
With such numerous advantages of the illumination devices using LED, problems however arise due to large heat generation from the high-output LED. For example, heat generated from the LED element needs to be dissipated effectively, in order to prevent the LED element from degrading.
Accordingly, there have been known LED illumination devices configured to have a substrate having mounted thereon LED elements for illumination, a base for fixing the substrate, and a heat pipe or a heat sink composed of radiation fin or the like, which transfers heat generated from the LED.